Abstract: A steering system (1) for vehicles including a front wheel steering mechanism (1a) for steering front wheels (5) at an angle in accordance with a steering operation of a driver, and a rear wheel steering mechanism (1b) for steering rear wheels (11) at an angle (Sr) in accordance with a travelling state of the vehicle. For the steering of the rear wheel, a reference steering angle (Ar) according to a turning state of the vehicle and a corrective steering angle (Ac) according to a velocity derivative thereof are computed, and the steering angle (Sr) of the rear wheel is obtained by making either an addition or a subtraction of the reference and corrective steering angles at least in accordance with the velocity derivative.

Abstract: A steering system for a vehicle with a steerable front wheel (5) and a rear wheel (11) controlled to be steered in accordance with a travelling state representative quantity (.delta..sub.f, V, .alpha..sub.a), wherein the rear wheel is steered taking into account at least a ratio of a cornering power (Kr) thereof to a vertical load on the tire thereof, besides the travelling state representative quantity.

Abstract: The method of the present invention improves the damping property of the yaw motion of the vehicle by feeding back a detected yaw rate value in a dynamic sense for compensating the front wheel steer angle so as to increase the damping coefficient of the yaw motion of the vehicle. By controlling the front wheel steer angle by accounting for not only the proportional term of the steering wheel input angle but also the derivative term which is proportional to the steering wheel input angular speed, in the feed-forward control of the front wheel steer angle in relation with the steering operation by the driver, and by appropriately varying the control parameters of the yaw rate feed-back and the steering wheel input feed-forward, the yaw response of the vehicle can be made proportional to the steering wheel input, and the response delay in the yaw rate against the steering wheel input can be reduced to substantially zero.

Abstract: The maneuvering area of a front and rear wheel steering vehicle is minimized by making the rear wheels follow the trajectories of the front wheels. This can be accomplished by steering the rear wheels so that they may coincide, in a spatially fixed absolute coordinate system, with the steer angles of the front wheels when they were located at the same locations as the current positions of the rear wheels. Further proposed is an algorithm for achieving the required rear wheel steering control which comprises the steps of detecting the yaw angle of the vehicle body and subtracting from the steer angles of the front wheels at the time point when the front wheels were located at the current positions of the rear wheels, the change in the yaw angle of the vehicle body from the said time point to the current time point.

Abstract: A steering system for the front and rear wheels of an automotive vehicle comprises a front wheel steering mechanism having an output shaft, a rear wheel steering mechanism having an input shaft coupled to the output shaft, an output member for steering the rear wheels, and a motion converting mechanism for converting rotation of the input shaft to movement of the output member, a vehicle speed sensor, and a control unit connected to the vehicle speed sensor for controlling operation of the motion converting mechanism dependent on the vehicle speed detected by the vehicle speed sensor.

Abstract: A wheel alignment control system for a vehicle having at least one pair of rear road wheels opposing each other in the transverse direction of the vehicle, for changing and setting a wheel alignment factor of the wheels in relation to a current speed of the vehicle. The wheel alignment factor to be set by the control system is a camber angle of the rear wheels, a static toeing angle of the rear wheels, or a dynamic toeing angle of the rear wheels. The dynamic toeing angle of changed to be set by changing a stroke characteristic of each of a pair of suspenion units respectively supporting the rear wheels, on which the stroke characteristic of an associated one of the suspension units exerts an effect such that, in accordance with a stroke length thereof, the toeing angle of a corresponding one of the rear wheels is varied.

Abstract: A steering system for a motor vehicle includes a centering mechanism for establishing a neutral steering position. The steering system includes a steering wheel and a steering assembly for steering vehicle wheels in response to angular movement of the steering wheel. The centering mechanism is mounted on at least a portion of the steering assembly for establishing the neutral steering position of the steering assembly.

Abstract: A steering system for the front and rear wheels of an automotive vehicle comprises a front wheel steering mechanism having an output shaft, a rear wheel steering mechanism having an input shaft coupled to the output shaft, an output member for steering the rear wheels, and a motion converting mechanism for converting rotation of the input shaft to movement of the output member, a vehicle speed sensor, and a control unit connected to the vehicle speed sensor for controlling operation of the motion converting mechanism dependent on the vehicle speed detected by the vehicle speed sensor.

Abstract: Disclosed is an actuator for steering the rear wheels in front and rear wheel steering device for vehicle in which the external forces, such as the self aligning torque of the rear wheels and irregularities of the road surface, which may be applied to the rear wheels are prevented from being transmitted to the actuator for controlling the steering angle of the rear wheels. Thereby, the steering angle of the rear wheels are determined solely by the control action of the front and rear wheel steering device and the motion of the vehicle is not affected by external forces. As a result, the vehicle motion is stabilized. When the force for steering the front wheels is transmitted to the rear wheels to steer them, elimination of the reaction from the road to the actuator prevents undesirable variation in the force required to steer the vehicle or the force required to hold a steering angle.

Abstract: In a front and rear wheel steering device for a vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, by accounting for the magnitude of vehicle acceleration in determining the steering angle ratio of the rear wheels by using a mathematical function in the form of f(u) - g(u')where u is a vehicle speed and u' is a change rate of the vehicle speed, it is possible to reduce the slip angle of the vehicle to zero irrespective of the vehicle speed and the vehicle acceleration and the phase delay of the lateral response of the vehicle can be reduced, whereby the driveability of the vehicle is substantially improved and, thus, driving a car can be made easier, safer and less tiring.

Abstract: The front and rear wheel steering device of the present invention not only has a means for allowing the manual selection of a mathematical function which determines the steering angle ratio of the rear wheels relative to the front wheels from a plurality of mathematical functions but also has a means for limiting such a manual selection depending on the condition of the vehicle. Since manual selection of a mathematical function for the steering angle ratio may not be appropriate under certain vehicle conditions, the device of the present invention limits such a manual selection when the vehicle speed, the vehicle acceleration, the shift position of the transmission, the steering speed or the steering acceleration is greater than a certain value. Thereby, the convenience of the manual selection of the steering angle ratio is preserved yet any undesirable vehicle response from improper manual selection of the steering angle ratio is prevented.

Abstract: An actuator for steering the rear wheels in front and rear steering device for a vehicle in which the steering angle of the rear wheels can be manually neutralized should the actuator fail with the rear wheels steered to a certain angle. The actuator may be a type which either directly steers the rear wheels following command from control means or varies the state of means for setting up the steering angle ratio of the rear wheels. In either case, a preferably detachable handle may be engaged to an output end of power means of the actuator. Thus, the situation in which the rear wheels are frozen at a certain steering angle and the driving of the vehicle becomes difficult is safely avoided.

Abstract: A front and rear wheel steering device which varies the steering angle ratio of rear wheels relative to the steering angle of front wheels in relation with vehicle speed is utilized to improve the drive response of a vehicle, as well as to improve the maneuverability of the vehicle. By varying the steering angle ratio which is a function of vehicle speed according to the running condition of the vehicle, the interference of the running condition of the vehicle upon the driving response can be reduced. The driving response may be evaluated in terms of yaw rate or lateral acceleration of the vehicle for a certain steering input. The running condition of the vehicle may comprise any combination of vehicle acceleration, friction between tires and the road surface, load acting between front wheels and the road surface, and load acting between rear wheels and the road surface.

Abstract: In a front and rear wheel steering device for a vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, by accounting for the magnitude of vehicle acceleration in determining the steering angle ratio of the rear wheels by selecting a mathematical function from a plurality thereof, the vehicle response particularly in high speed range can be improved. Smooth transition from a certain characteristics to another may be achieved either by preparing a number of mathematical functions of vehicle speed for the steering angle ratio of the rear wheels or providing some time delay in the transition from one characteristics to another, preferably in proportion to the magnitude of the vehicle acceleration.

Abstract: In a front and rear wheel steering device contive for vehicle in which the steering angle ratio of the rear wheels relative to the front wheels is variable according to the vehicle speed, provision of a manual selection means for fixing the steering angle ratio to certain fixed values which may be either positive or negative can greatly improve the maneuverability of the vehicle in both high speed and low speed ranges. However, inadvertent manual selection of the steering angle ratio is not desirable since it may cause a sudden change in the steering angle of the rear wheels. Therefore, this invention provides means for preventing the manual selection of the steering angle ratio when it is not proper. This means may be an active prohibition control of manual steering angle ratio selection means, an alarm to warn the driver or a vehicle speed control which limits the vehicle speed.

Abstract: In a front and rear wheel steering device for vehicle for variably controlling the steering angle ratio of rear wheels relative to the steering angle of front wheels according to a certain mathematical function of vehicle speed in such a manner that the rear wheels are steered in opposite phase relationship in a low speed range and in same phase relationship in a high speed range, by providing a selection means for manually selecting a special mathematical function for an extremely low speed range which will cause a same phase relationship at an extremely low speed and a smooth transition to the certain mathematical function, parking the car along a curbstone and changing the lateral position of the vehicle in a limited space are simplified since the rear part of the vehicle will not swing laterally.

Abstract: A motor vehicle has two steerable righthand and lefthand front wheels and two steerable righthand and lefthand rear wheels, a front wheel steering device for steering the front wheels according to the angle through which a steering wheel is turned, a rear wheel steering device for steering the rear wheels, an actuator for actuating said rear wheel steering device, and a control device for controlling the operation of the actuator to steer the rear wheels in a direction which is selectively the same as or opposite to the direction in which the front wheels are turned. The steering of the rear wheels is controlled by determining the speeds of rotation of the four front and rear wheels with respect to the ground, and controlling the operation of the actuator with the control device so that any difference between the speeds of rotation of the front and rear wheels with respect to the ground will be reduced substantially to zero.

Abstract: A steering system for a vehicle with a front wheel and a rear wheel, in which the rear wheel is steerable in relation to a steering operation of the front wheel, such that a ratio control of a steered angle ratio of the rear wheel to the front wheel is effected to be variable in accordance with a travelling speed of the vehicle. The steering system is provided with a mode selecting unit adapted to be manually operable for exclusively setting an arbitrary one of a plurality of control modes of the ratio control. The steering system may be further provided with a time-delay unit for gradually effecting the ratio control, when changing one of the control modes to another thereof.

Abstract: A steering system for vehicles in which the steered angle ratio of a rear wheel to a front wheel is controllable in accordance with the vehicle speed. The steering system is provided with a manual switch device for selecting to set an arbitrary one of a plurality of predetermined steered angle ratios. The steering system may be further provided with a switch lock device for locking the switch state of the manual switch device. The switch lock device may be actuated when the vehicle speed is higher than a predetermined reference vehicle speed. Further, the switch lock device may be actuated when a reduction gear is shifted to a shift position having a relatively low reduction ratio. The switch lock device may also be actuated when the steered angle of the front wheel is larger than a predetermined value.

Abstract: A steering mechanism in a motor vehicle having front and rear wheels steerable in response to steering operation of a steering wheel. An input shaft rotatable about its own axis in response to steering operation of the steering wheel has an eccentric shaft mounted on a rear end of the input shaft. A tubular member is rotatably fitted over the eccentric shaft and has an integral pinion and an integral eccentric cam. An internal gear disposed in fixed relationship to a vehicle body of the motor vehicle is held in meshing engagement with the pinion. A pair of tie rods supporting the rear wheels, respectively, is interconnected by a joint member rotatably mounted on the eccentric cam.